How Much Power Can It Take to Run a Map Light?

I got into my car Thursday night to make the short drive to church for choir rehearsal. I immediately got a bad feeling when I saw that one of the map lights had been left on and was glowing anemically. Sure enough, when I turned the key, I only heard the dreaded clicking sound—the battery had been drained. I began considering alternatives. I could walk, but I would be late (and perhaps tired) by the time I arrived. I could call AAA, but this would no doubt delay me even more. Besides, after the short drive to church, I would still have a dead battery. Instead, I ran into the house, grabbed my church directory, and began thinking of who passed near me on his way to church. I called one number and got an answering machine. My second call reached an alto who was running late. We agreed to meet on a nearby corner, so I ran out the door.

It was perhaps ten minutes before the cute little Volkswagen pulled over to the curb to let me in. While waiting, I had been watching cars negotiate a four-way stop. (This was the intersection that inspired my essay on this type of intersection.) It was interesting to note that not a single car—quite a few passed—actually stopped at the intersection except out of absolute necessity. Every car slowed down, usually to a very slow pace, but none literally stopped. I guess this has become the standard procedure for negotiating such an intersection. Anyway, I arrived at church 15 or 20 minutes late, enjoyed a good rehearsal, and got a ride home.

I decided to call AAA the next morning, as I had no early obligations. Once I was dressed, I made the call, and the car was running about 15 minutes later. I kept it running for two hours, by which time, the battery seemed to be fully charged. I was surprised that one map light could do so much damage. As it happened, I had not used the car Thursday until it was time for choir, so the map light—which I had turned on to read something after I had shut down the engine sometime Wednesday night—had been on for the better part of a day. Some quick mental calculations failed to convince me that the map light should have drained enough power to prevent the car from starting, but perhaps it is more of a glutton for electricity than I realize.

Be sure to turn the map light off when you park your car.